RU2046165C1 - Device for processing the wooden chips - Google Patents

Abstract

FIELD: wood-working industry. SUBSTANCE: roll projections in the device are made narrowing towards the top and have the height equivalent to the desired thickness of the chip. EFFECT: simpler design. 8 cl, 6 dwg, 4 tbl

Description

 The invention relates to the pulp and paper industry, in particular to a device for processing wood chips.

 In a conventional papermaking process, logs are unloaded and turned into chips, after which individual cellulose fibers are separated from the chips for further processing and formation of paper rolls. A common method for separating cellulosic fibers consists of boiling wood chips in a chemical solution at high temperatures and pressures in digesters to remove lignin from the chips that hold the fibers together. For further papermaking, it is desirable that the resulting de-lignin fibers have substantially the same properties. To reduce the production of undigested or overcooked chips in digesters, it is necessary that the penetration of the cooking liquor into the chips is the same for all chips so that the effects of temperature, pressure and time are the same for all chips. Therefore, it was found desirable to use a device for sorting chips, which simultaneously removes incomplete and extraordinary size chips so that incomplete can be processed separately, and excessive pass through a device designed to reduce the size of the chips before it is boiled out.

 The device used to reduce the size of excessive chips separated from the flow of chips by means of partitions is a knife for cutting chips. The main operation of the cutting knife is the operation of the rotor in the drum, in which excessively sized chips are driven under the knife and processed by it to an acceptable thickness. An example of a knife for trimming chips can be a knife described in US patent N 4235382, issued in the name of William S. Smith, on "Method and device for grinding wood chips."

 The disadvantage of the invention is that the chip cutting knives do not provide chip processing to the optimum size when they are blunt, or if they do not meet the speed or load when reducing non-standard sizes, they tend to produce too small chips.

 Interactive rolls are known for treating oversized chips by compression, which affect the penetration of the solution in the chips.

 In the known invention, the rolls closely interact with the device for guiding the chips with a sharp end into a branch between the rolls, with rollers compressing the chips across their thickness to at least one fifth of their original thickness, but not more than up to one tenth of their original thickness. After this, the chips are given the opportunity to be heard to their original shape with a break in the fibers in them with increasing porosity of the chips.

 In known inventions, opposing closely interacting rolls or splitting rolls compress the chips to break the fibers therein. The rolls are made smooth so that the effect on the chips is only compressive, due to which the structure of the chips does not change except for breaking the fibers.

 The chips tend to clog into the recess above the rolls, and in particular, the largest chips, which require splitting more than others, get stuck between the rolls in the upper part of the pair of rolls, and do not extend between them.

 Destructuring or splitting is unacceptable as a normal processing process due to the low productivity of the splitting devices and the subsequent effect on the digestion operation.

 The purpose of the invention is the creation of a device for processing chips with a size that reduces the time required for boiling out, and therefore, achieves a level of decalcification to obtain masses that have the same characteristics and properties.

 Another objective of the invention is to provide a device for processing excessive chip sizes quickly and efficiently with fast transmittance while minimizing congestion or clogging of the device.

 Another objective of the invention is to provide a device for processing wood chips, which splits or crushes the excessive size of the chips without the formation of small chips or chips, easy to use, which requires minimal adjustment for optimal operation.

 Another objective of the invention is to provide a device for processing wood chips to increase the speed of impregnation with a solution, in particular large chips, and to create a device for the destruction of wood chips, which would not depend on the specific orientation of the chips between closely interacting rolls.

 The goal is achieved by performing closely interacting opposed rotating rolls having aggressive surfaces. In a preferred design, the rolls have pyramidal protrusions made by machining on their surfaces. In a preferred embodiment, the peaks of the pyramids are half an inch apart from each other and the processing depth from the peak to the base of the individual pyramid is about a quarter of an inch. During operation, the peaks of the rolls can be placed with peak-peak or peak-trough orientations. In the process, the chips are crushed in the direction of orientation of the fibers, and with the help of this device they will be split regardless of how much the chips enter the clip between the rollers.

 The invention differs from the known devices intended for destructuring or splitting in that the aggressive surface of the rolls is used not only to compress the chips, but also to break or break the chips in thickness.

 Figure 1 shows a device for splitting wood chips; figure 2 section aa in figure 1; figure 3 part of the surface of one of the rolls of the device for splitting wood chips; figure 4 is a partial view from the end of one of the pairs of rolls in the device for splitting wood chips; figure 5 another orientation of the roll; Fig.6 is the same, another orientation of the roll.

 Wood chips into the device 1 is supplied from a switchgear 2, which delivers an even stream of wood chips 3 to the pairs of upper and lower rollers 4 and 5. The pairs of rollers 4 and 5 are located in the housing 6, which has an upper hole 7, through which the wood chips 3 pass, and a lower hole 8 through which the treated wood chips exit the device. The incoming chip stream 3 is guided by the blades 9 and 10 to the upper pair of rolls 4, and the chips passing through the upper pair of rolls are guided by the blades 11 and 12 to the lower pair of rolls 5. The transporting mechanism transfers the processed chips from the device 1 to the next process steps.

 The upper pair of rolls 4 includes rolls 13 and 14, located next to the opposite rotating so that in the upper recess between the rolls of the surface moved to a narrow zone formed by closely interacting rolls 13 and 14, as shown by arrows 15 and 16.

 The lower pair of rolls 5 includes rolls 17 and 18, closely spaced and opposed to rotate so that in the upper recess between the rolls, the surfaces extend to a narrow zone formed by closely spaced rolls 17 and 18, as shown by arrows 19 and 20.

 Each of the rolls 13, 14, 17, 18 rotates in bearings 21, a drive mechanism 22 is provided for rotating the rolls. The drive mechanism 22 includes a motor 23 or other energy source and a drive gear 24. Each drive gear 24 drives each of the rolls, however, sometimes it is necessary to drive only one roll from each pair of rolls. A smooth roll in each pair of rolls, opposite to the rotating roll, can be idle, thereby reducing energy demand, since when the chips are not fed into the device, only one roll of each pair is driven. When the chips enter the device and wedge between the rotating and non-rotating rollers, the non-rotating roller will rotate, contributing to the splitting and passing through the wood chips.

 The distribution mechanism 22 comprises a housing 25 having an opening 26 for receiving chips from the chip supply mechanism, a distribution screw 27 for equalizing the flow of chips along the distribution mechanism and the distribution grid 28, through which the chips pass from the distribution mechanism 22 to the first pair of rolls 4. Distribution screw 27 is driven by an appropriate energy source 29 and rotates in bearings 30 in the housing 25.

 In known installations, only one pair of rolls or more than two pairs of rolls is used, and the mechanism for supplying chips to a pair or pairs of rolls may be of different types than the distribution mechanism 2 described above.

 The surfaces of the rolls used in the present invention differ from the surfaces of the rolls used to split chips earlier in that the surfaces of the rolls have an aggressive contour. In the exemplary embodiment shown in FIG. 3, the surface of the roll is the basis of the pyramidal projections 31, which are formed by machining the surface of the roll with the circumferential execution of V-shaped grooves 32 and axial V-shaped grooves 33 on the roll at right angles. Due to the machining of such intersecting troughs on the surface of the roll, four-sided pyramids are formed, lying radially outward. Each of the protrusions 31 has a peak 34 formed by the remaining material of the outer parts of the machined surface of the roll, and the base 35, limited by the depth of the intersecting grooves 32 and 33 in the material area of the machine. Typically, both roll roll pairs have surfaces of the same configuration, however, it is possible to have one roll in each pair smooth or have a more aggressive or less aggressive surface contour than the surface contour of another roll in the roll pair.

 In one design, a roll surface was formed on which peaks 34 were placed half an inch apart from each other and each peak had a smooth surface of about one sixteenth of an inch squared. The depth of each pyramid from peak 34 to the base was 35 mm.

 When using and operating a device for destructuring wood chips, the chips are fed to the distribution mechanism 2, and from the distribution mechanism 2 evenly along the axial length of the first pair of rolls 4. The chips from the previous sorting stage that include only excessive chip size can be included in the distribution mechanism 2 separated at the previous stage of sorting, or the entire stream of chips to be processed into wood pulp in the device.

 It is possible to separate only the incomplete size from the entire stream of chips and then process the chips of an oversized size and an acceptable size by the proposed device.

 The device can pass a large volume of chips, providing the ability to process the entire stream of chips in the machine with the exception of screening of excessive chips. When passing through an oversized chip, there is no need to separate the oversized chips for separate processing. Small shavings passing through the respective rolls will pass through the device unprocessed and in this case only super-dimensional shavings will be split. After processing an acceptable and oversized chip size, the processed chips will equally correspond to the process of wood pulp formation.

 From the distribution mechanism 2 chips enter the area above the pair of rolls. The rollers can rotate separately, and their positions are controlled so that they align with the peaks with the orientation of the grooves as shown in FIG. 4. In another embodiment, the orientation of the rolls is controlled by the peak-to-peak orientation, as shown in FIG. In yet another process where, in addition to splitting, compression is desired, or where fine chip thickness remains fine, a closely interacting peak-gutter ratio may be desirable, as shown in FIG. 6. In other operations, where the energy supply to the device is minimized, one roll of each roll pair is driven, while the others remain idle. When the chips come to the rolls and are clamped between them, the idle roll is driven by the drive roll through the drive connection formed by the wood chips sandwiched between them.

 When chips pass between pairs of rolls regardless of orientation, the chips tend to split or crack parallel to the orientation of the fibers in the chips. This occurs regardless of whether the chips pass between the rolls along or end to front.

 When the peak-gutter orientation is used, as shown in FIGS. 4 and 6, together with pyramidal protrusions half an inch apart and 6 mm high, cracks appearing in the chips occur about every quarter inch. The resulting intermediate distance between the cracks corresponds to an acceptable chip thickness in wood pulp operations. When cracking on large surfaces of the chips, holes appear that facilitate the penetration of the solution. The rupture of the fibers resulting from compression, the penetration of the solution into the chips contribute to the holes created by cracks. The material displacement at the cracks is greater for thick chips than for thin ones, and as a result of this, the holes for penetration of the solution are less clogged in thick chips than in thin ones, thereby equalizing the rate of penetration of the solution in thick and thin chips. Due to the fact that the rolls are at a distance from each other, the middle of the chip does not move, although the displacement at the cracks can be significant and the chip will remain intact without the formation of small particles, chips or broken chips.

 In those cases where a plurality of vertically arranged roll pairs are used, as shown in FIGS. 1 and 2, it is advisable to provide smaller roll spaces in the lower roll pairs. In this case, excessively exceeding the standard size of the chips will be compressed and / or crushed by the upper rollers with the formation of acceptable or minimally exceeding the standard size of the chips passing through them. The following roll pairs will additionally process significantly exceeding the standard size and minimally exceeding the standard chip size.

 Laboratory studies of the conversion to pulp were carried out on chips treated with one pair of rolls, on which the protrusions of adjacent rolls are in mutual engagement, as shown in Fig.6. For control, one sample was not processed, and other samples were cut into pieces by known machines for cutting thick chips. Several samples were treated with so-called soft processing, while others were processed with hard processing. In soft machining, the distance between the protrusions in the area where the protrusions from each roll have the smallest distance from each other is 6 mm. In hard machining, the smallest distance between the protrusions of the rolls was 3 mm.

 Table 1 shows the characteristics of the various samples on which the studies were conducted.

 Samples were sorted by the CC2000 chip classifier (Prader Companie). The samples were divided into small change, which passes through a 3 mm round hole, chips from 0 to 2 mm thick; acceptances from 2 to 8 mm thick; all had a thickness of more than 8 mm; the rest had a thickness of more than 14 mm. Table 2 shows the thickness characteristics of each sample.

 In all samples, with the exception of those in which super-thick chips were cut, 50% or more of the chips in each sample were larger than the maximum set acceptable thickness of 8 mm. Several samples included a large percentage of ultra-thick chips, more than 14 mm.

 Samples were boiled in a laboratory digester using the Kraft boiling method. Several samples were boiled in separate batches under separate boiling conditions. One batch was boiled using a mixture of 15% (85% of the chips from samples 3 and 4). The cooking conditions for each batch and the type of chip sample are described in Table 3.

 Strength properties of the mass were calculated after cleaning the digested mass for 30,000 rpm. Table 4 shows the results.

 As can be seen from table 4, the length of the fault and elongation did not change under the influence of the chip splitting process. Both planed and split chips had the same strength characteristics. However, rupture, strength, and tangling rates are lower for split chips.

 Fewer gaps were noted among the grinding range with the smallest gaps in the chips during their tough machining. When mixed with breakable chips, the gaps in the mass from the combination of samples 3 and 4 were greater than for broken chips (sample). Therefore, mixtures of fissile chips with conventional chips are considered acceptable for the formation of wood pulp.

 Wood pulp from shavings treated with the device according to the invention had minimal reject levels and significantly lower than in the mass of broken shavings. The overall output of the digester was lower for chips processed according to the invention.

 The tool for processing excessive chip sizes provides a suitable, acceptable wood pulp having characteristics similar to those obtained from an acceptable chip size. The device reduces the formation of fines and defective fibers.

Claims (9)

 1. A device for processing wood chips, comprising a housing with an inlet for loading chips and an outlet for unloading the processed chips, means for supplying a stream of wood chips and its distribution along the entire length of the gap of a predetermined value formed between at least one pair of parallel rolls, mounted in the housing with the possibility of rotation, at least one of which in a pair of rolls is connected with a drive of rotation, and on the surface of at least one of the rolls in a pair made many ystupov, characterized in that the protrusions are tapered towards the top and have a height equivalent to the desired chip thickness.  2. The device according to claim 1, characterized in that the protrusions are made on the surface of both rolls in a pair, while the shape and location of the protrusions on the surface of one and the other rolls in a pair are identical.  3. The device according to claims 1 and 2, characterized in that the protrusions are in the form of pyramids.  4. The device according to paragraphs. 1 3, characterized in that the protrusions are in the form of regular tetrahedral pyramids, the bases of which are adjacent to each other.  5. The device according to PP.2 to 4, characterized in that the rolls in a pair are installed with the possibility of placing the vertices of the protrusions of one roll opposite the vertices of the protrusions of another roll in the gap between the rollers.  6. The device according to PP.2-4, characterized in that the rolls in a pair are installed with the possibility of placing the vertices of the protrusions of one roll opposite the troughs of another roll in the gap between the rolls.  7. The device according to PP.2 4 and 6, characterized in that the rolls are paired with the possibility of placing the vertices of the protrusions of one roll in the troughs of another roll in the gap between the rolls.  8. The device according to paragraphs. 1 and 2, characterized in that the protrusions are in the form of axisymmetric figures and their axes are located radially with respect to the surface of the roll.  9. The device according to claims 1, characterized in that the distance between the peaks of the protrusions is essentially equal to their height.

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